Since 1983, efforts to promote vaccination have been accompanied by a significant reduction in measles morbidity and mortality. However, vaccination coverage is not high enough to interrupt transmission of the virus, despite recent catch-up campaigns. The combination of this insufficient vaccination coverage and low viral circulation over the past several years has led to a high level of susceptibility to the disease among older children. The Sentinelles surveillance system is currently unable to identify areas of residual measles transmission and does not allow for determining the proportion of measles cases among clinically suspected cases. Consequently, a low proportion of true measles cases can be expected. Ultimately, surveillance tools will need to provide comprehensive reporting, a broad clinical definition, biological confirmation, strain typing, measurement of vaccination coverage for each dose, and an estimate of the proportion of the susceptible population through modeling or serological studies.